MOSgated drivers which are circuits commonly integrated into a monolithic chip are known for providing output signals which can trigger the gate of a high side power MOSgated device. A typical MOSgate driver is the IR2110 driver made and sold by the International Rectifier Corporation, the assignee of the present invention. Such devices are also described in copending application Ser. Nos. 08/299,561, filed Sep. 1, 1994, entitled "MOSgate Driver Integrated Circuit, etc." and 08/273,695 filed Jul. 12, 1994, entitled "Reset Dominant Level-Shift Circuit, etc.".
Such drivers also have means for turning off the high side device if a fault or predetermined overcurrent (both hereinafter sometimes referred to as a fault condition or fault current) flows through the main power device and to provide an output signal indicating the presence of the fault. The delay time for shutting off the main power device includes the delays which are inherent in the latch circuits in the high and low sides of the driver. Thus, it is common to have all low side (low voltage to ground) circuits on the monolithic chip body and the high side circuits in a floating well in the chip surface. Such structures are shown in copending application Ser. No. 08/299,561, referred to above. Therefore, in the event of a fault or overcurrent, a sensing signal in the high side circuit is level-shifted down, through two PMOS devices which control the inputs to set and reset latches respectively of a filter and latch circuit in the low side of the circuit. This latch then produces a fault input to the control logic circuit on the low side of the circuit and also causes the report of the fault condition. The control logic then produces a turn-off signal which is level-shifted to the high side and to a high side filter and latch which remove the output signal to the MOS-controlled power device.
This circuitry introduces the delay of the filters in both the high side and low side latches into the minimum time needed to turn off the power MOSgated device.